Recoil-operated firearm



Jan. 24, 11939. T. F. SANDERS RECOIL-OPERATED FI REA RM Filed Nov. 2,1937 Patented Jan. 24, 1939 UNITED STATES PATENT OFFECE RECOIL- OPERATEDFIREARM Thomas Frederick Sanders, Slough, England, assignor to SandersSmall Arms Limited, London, England Application November 2, 1937, SerialNo. 172,433 In Great Britain December 5, 1936 Claims. (01. 89-3) Theinvention relates to recoil-operated firediagrammatically theapplication of the invention arms and is more particularly directed toarto a sub-machine gun. To render the represenrangements for unlockingthe breech bolt after tation clearer certain parts having no relation ashot has been fired and retaining the looking to the invention have beenomitted, such as the.

5 mechanism in the open position until the bolt cartridge feed, which isefiected in an oblique 5 has returned to the locking position ready forthe upward direction, and the firing mechanism. firing of a freshcartridge. In the figures:

The arrangement used according to the present Figure 1 is a sideelevation of the assembly in invention avoids unnecessary frictionbetween the firing position taken in section partly on the the bolt andthe locking member in this simple centre line and partly near the righthand side 10 type of mechanism and thus provides a re-loading of thegun,

mechanism suitable for sub-machine guns and Figure 2 is a correspondingview immediatedly other quick firing weapons as well as pistols, afterfiring a shot, rifles and light ordnance. Figure 3 is an elevation andFigure 4 an end According to the invention a recoil-operated elevationof a part of the stand, 15

gun mounted on a support to recoil longitudinally Figure 5 is a plan ofthe breech casing, thereon against resilient means comprises in com-Figure 6 is an elevation of the breech bolt bination a locking membermovable parallel to partly in section, itself and adapted in oneposition to hold the Figure '7 is a plan of the locking piece,

breech bolt in place for the firing of a cartridge Figures 8 and 9 areelevation and end eleva- 20 and in another position to release the boltand tion respectively of the same, and allow it to carry out the usualre-loading move- Figure 10 is a perspective view of the detent ments,guiding surfaces or the like between the mechanism. locking member andthe recoiling parts so ar- Referring to the figures, the breech casing lis ranged that in operation the only movement of mounted on the stand 2by means of grooves 3 5 the locking member in relation to the recoilingso as to be free to slide in a longitudinal direcparts is substantiallyperpendicular to the barrel, tion. The barrel is partly shown at 25 inFigures oblique guiding surfaces or the like between the l and 2. Aspring 6 tends to keep the parts in looking member and the support soarranged that the position of Figure 1 or to return them to it inoperation the only movement of the locking after recoil. 30 member inrelation to the support is in the direc- The stand 2 is provided withtwo upright walls tion of the said oblique guiding surfaces or the 5projecting into the breech casing l to cooperlike, a detent normallyholding the breech casing ate in the locking arrangements as will beshown in the recoiled position, and means actuated by later. The breechbolt 5 slides back between these the bolt for releasing the detent asthe bolt rewalls when unlocked to perm't a spent cartridge turns to thefiring position. to be ejected and a new one to be inserted into the Ithas already been proposed to actuate a lockbarrel by the usual wellknown mechanisms. The ing member by a combination of oblique andperresidual gas causes the rearward movement of Dendicular guidingSurfaces, but the y arrangethe bolt 5. Due to this movement therecuperator 40 ments of this kind providing a Small t d a spring I iscompressed and then returns the bolt 40 ex u sion f e locking me r ep ne solely e to the firing position with a new cartridge in on the lockingmember itself for the retention of l c In Figure 2 the bolt is unlockedand has the breech casing in the recoiled position until just tarted,its rearward movement. the bolt had returned to the firing position. Thebolt, shown separately in Figure 6 has a It has also n p p to p vide arecoilstep 8 facing rearwards by which it is locked in 45 operated gunwith a detent for holding the breech the firing position. The front faceH] of a lockcasing back until the return of the breech bolt ing piece 9,shown separately in Figures '7, 8 and 9, to the closed position inconjunction with a abuts against the step 8 to lock the bolt in thebreech bolt locking member not guided by oblique firing position. Theconstruction of the parts by and perpendicular surfaces in the manneraforemeans of which the locking piece 9 releases the 50 said but movingtransversely in relation to the bolt 6 at the appropriate time will nowbe debarrel and breech bolt to unlock the bolt and scribed. thereafterlongitudinally with the bolt along the The locking piece 9 may beconsidered as havsupport. ing an elongated body it and four legs I2 pro-The accompanying drawing serves to illustrate jecting obliquely forwardsand downwards. Sub- 55 stantially vertical shoulders I3 at the upperends of the legs I2 face rearwards and abut against correspondingforward faces I 4' of the breech casing. The locking piece 9 is thuscapable of bodily, substantially vertical movement only in relation tothe breech casing, and when it rises high enough the front face I clearsthe step 8 on the breech bolt 6, allowing the latter to recede and carryout the usual reloading movements. This position is clearly shown inFigure 2 where the body of the locking piece, being in section, appearsas a hatched rectangle.

The locking piece is also guided in relation to the stand and thedirection of guiding is obliquely rearwards and upwards on recoil. Forthis purpose the four legs I2 fit accurately in 0blique slots I5 cut inthe walls 5 on the top of the stand. The vertical position of thelocking piece 9 is thus always determined by the relative horizontalpositions of the breech casing and stand, being brought to the unlockingposition at the end of the recoiling movement of the casing.

When the breech casing I has recoiled, a detent I6 pivoted at I! on thestand 2 is urged by 'a spring I8 into a notch I9 cut in the lower righthand edge of the breech casing. The breech casing and associatedrecoiling parts are thus held in the recoiled position by means entirelyapart from the breech bolt 6 and locking member 9.

To release the recoling parts after the reloading movements have beenaccomplished by the bolt 6 a bell crank lever 20 is pivoted at 2I on thestand 2. This lever has one arm 22 approximately horizontal at the righthand side of the gun to bear on the under side of a tail of the detentI6 projecting forwards. The other arm 23 is roughly vertical and is onthe centre line of the gun to engage a groove 24 on the under side ofthe bolt 6. As the bolt reaches its firing position the end of thegroove 24' catches the arm 23, so that the arm 22 is raised and tips thedetent I6 out of the notch I9. The spring 4 then returns the recoilingparts to their normal firing position, bringing the locking piece 9 backto the locking position ready for the next shot.

The action of the gun will now be recapitulated. On the firing of a shotthe barrel and the breech casing I recoil against the spring buffer 4.During this movement the locking piece 9 rises vertically in relation tothe breech casing as its legs I2 slide in the oblique slots I5 of thestand. When the front face ID of the locking piece has risen high enoughto clear the step 8 on the breech bolt 6 the latter recedes and carriesout the reloading movements in the usual way. Meanwhile the detent I6holds the breech casing in the recoiled position by clicking into thenotch I9.

It is only when the bolt .6 has returned to its forward position that ittrips the detent I6 by means of the lever 20. The spring 4 then restoresthe breech casing and barrel to the firing position, and this relativemovement causes the descent of the locking piece 9 in just the same wayas the recoiling movement caused it to rise. The bolt is then locked andthe gun is ready to fire another shot.

Obviously the various parts will be so' dimensioned in relation to theammunition to be used that the bolt is not unlocked until the bullet hashad time to reach a predetermined position in its flight.

What I claim is: r V r 1. A recoil-operated gun comprising in com-.bination a support, resilient means, a breech casing and barrel mountedon the support to recoil longitudinally against the resilient means, abreech bolt in the casing arranged to travel rearwards after firing andthen forwards to re-load the gun, a locking member movable bodily intoand out of a position in which it locks the bolt in the firing position,a guiding surface fast with the breech casing substantiallyperpendicular to the barrel, a cooperating guiding surface on thelocking member in constant engagement therewith, an oblique guidingsurface on the support, a cooperating oblique guiding surface on thelocking member in constant engagement therewith, a detent biased to holdthe breech casing in the recoiled position, and means actuated by thebolt for releasing the detent as the bolt returns to the firingposition.

2. A recoil-operated gun comprising in combination a support, resilientmeans, a breech casing and barrel mounted on the support to recoillongitudinally against the resilient means, a breech bolt in the casingarranged to travel rearwards after firing and then forwards to reloadthe gun, a locking member movable bodily and having front and rearabutment surfaces substantially perpendicular to the barrel, a rearwardfacing surface on the bolt to engage the front abutment surface on thelocking member in one position thereof and to clear it in the otherposition, a forward facing surface on the breech casing in constantengagement with the rear abutment surface on the locking member, anoblique guiding surface on the support, a cooperating oblique guidingsurface on the locking member in constant engagement therewith, a detentbiased to hold the breech casing in the recoiled position, and meansactuated by the bolt for releasing the detent as the bolt returns to thefiring position.

3. A recoil-operated gun comprising in combination a support, resilientmeans, a breech casing and barrel mounted on the support to recoillongitudinally against the resilient means, a breech bolt in the casingarranged to travel rearwards after firing and then forwards to reloadthe gun, a locking member movable bodily and comprising a longitudinalbody with oblique legs projecting therefrom, front and rear abutmentsurfaces on the body of the locking member substantially perpendicularto the barrel, a rearward facing surface formed as a step on the bolt toengage the front abutment surface on the locking member in one positionthereof and to clear it in the other position, at least one forwardfacing surface on the breech casing in constant engagement with a rearabutment surface on the locking member, two upright walls on the supportone on each side of the path of the breech bolt, the walls havingoblique slots to accommodate and guide the legs of the looking member, adetent biased to hold the breech casing in the recoiled position, andmeans actuated by the bolt for releasing the detent as the bolt returnsto the firing position.

4. A recoil-operated gun comprising in combination a support, resilientmeans, a breech casing and barrel mounted on the support to recoillongitudinally against the resilient means, a breech bolt in the casingarranged to travel rearwards after firing and then forwards to re-loadthe gun; a locking member movable bodily into and out of a position inwhich it looks the bolt in the firing position, a guiding surface fastwith the breech casing substantially perpendicular to the barrel, acooperating guiding surface on the locking member in constant engagementtherewith, an oblique guiding surface on the support, a cooperatingoblique guiding surface on the locking member in constant engagementtherewith, a spring-biased detent pivoted on the support and located toenter a notch in the under side of the breech casing when the latter isin the recoiled position, a tail on the detent, a bell crank leverpivoted on the support and having one arm projecting rearwards under thetail of the detent, the other arm projecting upwards, and a forwardfacing surface on the under side of the bolt located to engage theupward arm of the bell crank lever when the bolt has nearly returned tothe firing position.

5. A recoil-operated gun comprising in combination a support, resilientmeans, a breech casing and barrel mounted on the support to recoillongitudinally against the resilient means, the breech casing having anotch on its under side, a breech bolt in the casing arranged to travelrearwards after firing and then forwards to reload the gun, a rearwardfacing abutment surface formed as a step on the top of the bolt, aforward facing abutment surface formed as the end of a groove on theunder side of the bolt, a locking member movable bodily and comprising alongitudinal body with four oblique legs projecting downwards andforwards therefrom, a front abutment surface on the body of the lookingmember located to engage the rearward step on the bolt in one positionof the locking member and to clear it in the other, rearward facingabutment surfaces projecting from the body of the locking member at thetops of the legs, forward facing abutment surfaces on the breech casingin constant engagement with the last named abutment surfaces, twoupright walls on the support one on each side of the path of the breechbolt, each wall having two oblique slots to accommodate and guide twolegs of the looking member, a spring biased detent pivoted on thesupport and located to enter the notch in the under side of the breechcasing when the latter is in the recoiled position, a tail on thedetent, a bell crank lever pivoted 0n the support and having one armprojecting rearwards under the tail of the detent, the other armprojecting upwards to engage the forward facing abutment surface on theunder side of the bolt and located to enter into the said engagementwhen the bolt has nearly completed its forward travel to the firingposition.

THOMAS FREDERICK SANDERS

